Great Planes 25% Pitts M-12S 50cc ARF - GPMA1421 - Manual (Page 39)

39
FLYING
Fuel Mixture Adjustments
A fully cowled engine may run at a higher temperature than
an un-cowled engine. For this reason, the fuel mixture should
be richened so the engine runs at about 200 rpm below
peak speed. By running the engine slightly rich, you will help
prevent dead-stick landings caused by overheating.
CAUTION (THIS APPLIES TO ALL R/C AIRPLANES): If,
while fl ying, you notice an alarming or unusual sound such as
a low-pitched “buzz,” this may indicate control surface fl utter.
Flutter occurs when a control surface (such as an aileron or
elevator) or a fl ying surface (such as a wing or stab) rapidly
vibrates up and down (thus causing the noise). In extreme
cases, if not detected immediately, fl utter can actually cause
the control surface to detach or the fl ying surface to fail, thus
causing loss of control followed by an impending crash. The
best thing to do when fl utter is detected is to slow the model
immediately by reducing power, then land as soon as safely
possible. Identify which surface fl uttered (so the problem
may be resolved) by checking all the servo grommets for
deterioration or signs of vibration. Make certain all pushrod
linkages are secure and free of play. If it fl uttered once, under
similar circumstances it will probably fl utter again unless the
problem is fi xed. Some things which can cause fl utter are;
Excessive hinge gap; Not mounting control horns solidly; Poor
fi t of clevis pin in horn; Side-play of wire pushrods caused
by large bends; Excessive free play in servo gears; Insecure
servo mounting; and one of the most prevalent causes of
fl utter; Flying an over-powered model at excessive speeds.
Takeoff
Before you get ready to take off, see how the model handles
on the ground by doing a few practice runs at low speeds on
the runway. Hold “up” elevator to keep the tail wheel on the
ground. If necessary, adjust the tail wheel so the model will
roll straight down the runway. If you need to calm your nerves
before the maiden fl ight, shut the engine down and bring the
model back into the pits. Top off the fuel, and then check all
fasteners and control linkages for peace of mind.
Remember to take off into the wind. When you’re ready,
point the model straight down the runway, hold a bit of up
elevator to keep the tail on the ground to maintain tail wheel
steering, and then gradually advance the throttle. As the
model gains speed decrease up elevator allowing the tail to
come off the ground. One of the most important things to
remember with a tail dragger is to always be ready to apply
right rudder to counteract engine torque. Gain as much
speed as your runway and fl ying site will practically allow
before gently applying up elevator, lifting the model into the
air. At this moment it is likely that you will need to apply more
right rudder to counteract engine torque. Be smooth on the
elevator stick, allowing the model to establish a gentle climb
to a safe altitude before turning into the traffi c pattern.
Flight
For reassurance and to keep an eye on other traffi c, it is a
good idea to have an assistant on the fl ight line with you. Tell
him to remind you to throttle back once the plane gets to a
comfortable altitude. While full throttle is usually desirable for
takeoff, most models fl y more smoothly at reduced speeds.
Take it easy with the Pitts M-12s for the fi rst few fl ights,
gradually getting acquainted with it as you gain confi dence.
Adjust the trims to maintain straight and level fl ight. After
fl ying around for a while, and while still at a safe altitude
with plenty of fuel, practice slow fl ight and execute practice
landing approaches by reducing the throttle to see how
the model handles at slower speeds. Add power to see
how she climbs as well. Continue to fl y around, executing
various maneuvers and making mental notes (or having your
assistant write them down) of what trim or C.G. changes may
be required to fi ne tune the model so it fl ies the way you like.
Mind your fuel level, but use this fi rst fl ight to become familiar
with your model before landing.
Landing
To initiate a landing approach, lower the throttle while on the
downwind leg. Allow the nose of the model to pitch downward
to gradually bleed off altitude. Continue to lose altitude, but
maintain airspeed by keeping the nose down as you turn onto
the crosswind leg. Make your fi nal turn toward the runway
(into the wind) keeping the nose down to maintain airspeed
and control. Level the attitude when the model reaches the
runway threshold, modulating the throttle as necessary to
maintain your glide path and airspeed. If you are going to
overshoot, smoothly advance the throttle (always ready on
the right rudder to counteract torque) and climb out to make
another attempt. When you’re ready to make your landing fl are
and the model is a foot or so off the deck, smoothly increase
up elevator until it gently touches down. Once the model is
on the runway and has lost fl ying speed, hold up elevator to
place the tail on the ground, regaining tail wheel control.
One fi nal note about fl ying your model. Have a goal or fl ight
plan in mind for every fl ight. This can be learning a new
maneuver(s), improving a maneuver(s) you already know,
or learning how the model behaves in certain conditions
(such as on high or low rates). This is not necessarily to
improve your skills (though it is never a bad idea!), but more
importantly so you do not surprise yourself by impulsively
attempting a maneuver and suddenly fi nding that you’ve run
out of time, altitude or airspeed. Every maneuver should be
deliberate, not impulsive. For example, if you’re going to do a
loop, check your altitude, mind the wind direction (anticipating
rudder corrections that will be required to maintain heading),
remember to throttle back at the top, and make certain you
are on the desired rates (high/low rates). A fl ight plan greatly
reduces the chances of crashing your model just because of
poor planning and impulsive moves. Remember to think.
Have a ball!
But always stay in control and fl y in a safe manner.
GOOD LUCK AND GREAT FLYING!